A primary source of noise in the bottling of soft drinks, beer and other beverages is the crowner machine which caps and seals the bottles after filling. Each of the three most widely used crowners includes a hopper, crowner face plate and crowner chute. Crowns are loaded in bulk into the hopper section and then introduced into the crowner face plate where they are properly oriented. The crowns are forced downwardly from the face plate along the crowner chute to the bottles for installation. To assure smooth operation of the crowner at economic production speeds, it has been found necessary to agitate the crowns within the hopper to avoid bunching or wedging prior to their introduction into the crowner face plate. In addition, some means must be provided to force the crowns downwardly along the crowner chute toward the bottles to be capped.
Agitation and movement of the crowns is normally accomplished by pressurized air forced through nozzles selectively located adjacent the point of connection between the hopper and crowner face plate, and along the length of the crowner chute. While assuring smooth handling and movement of the crowns, such air jets generate noise levels near the crowner in the range of 90 to 110 dBA. Such noise levels, if not physically harmful to the hearing, are at least distracting and uncomfortable to workers in the surrounding area.
In an effort to reduce the noise levels associated with the crowner air jets, at least two solutions have been proposed. First, mechanical agitation means have been provided at the hopper, face plate and/or crowner chute in combination with existing air jets to permit a reduction in the pressure of air forced through the jet nozzles which results in an accompanying reduction of the noise level. A second approach involves the use of silenced thrust nozzles with the same air pressure level as in existing devices. Generally, it has been found that the combination of mechanical and air agitation means is costly and difficult to retrofit to existing machines. While silenced thrust nozzles appear to be less costly and more easily retrofitted than the mechanical-air agitation means, such nozzles have proved to be relatively ineffective in reducing the crowner noise levels to any appreciable extent.